Function run_gc_with_debugger 

pub fn run_gc_with_debugger(input: &str) -> String

Execute Monkey source on the cycle-collecting VM, recording a snapshot at every debugger; statement, and return a tagged JSON envelope.

Both arms carry stdout, hits, and droppedHits: snapshots recorded before a runtime failure are exactly what the playground’s Debugger tab needs to explain that failure. Failures are data in the envelope, not JavaScript exceptions, mirroring run_gc_with_report.